Cub Engine Blowby. Is this a problem???

Red Farmer 84 · Mar 15, 2011

I have an early 70's cub tractor that I used for cultivating for the last few years. It cranks, runs and operates excellent. It has a moderate amount (but not too much) blowby smoke coming out of the dipstick area. The engine has tons of power and has good oil pressure (a little over the halfway point on the IH gauge with no numbers).

What could the problem be, and should I be concerned?? Is there an easy fix?

old · Mar 15, 2011

ALL engines have some blow by not matter how old or new but the new car engines take that blow by and runs it into the air in take and then burns it off. That cub does not have the burn off part to it so you see the blow by. Yes if way to much it can mean your rings are not sealing like they should and could cause a problem. One way to maybe help slow the blow by down some is to run a mix of
atf and gas 1 qt ATF to 5 gal of gas. That helps free up sticking rings and cleans the upper part of the engine

Jim Becker · Mar 15, 2011

(quoted from post at 15:39:29 03/15/11) That cub does not have the burn off part to it so you see the blow by.

Most Cubs have a tube that runs from the front side of the engine block to the intake pipe of the air cleaner. It isn't unusual to find these tubes plugged. If your tractor has one, remove it and clean the tube out. Also run a wire or something similar into the engine block where the tube connects to make sure the opening isn't plugged. This may take care of your visible blowby.

Red Farmer 84 · Mar 15, 2011

(quoted from post at 20:39:29 03/15/11) ALL engines have some blow by not matter how old or new but the new car engines take that blow by and runs it into the air in take and then burns it off. That cub does not have the burn off part to it so you see the blow by. Yes if way to much it can mean your rings are not sealing like they should and could cause a problem. One way to maybe help slow the blow by down some is to run a mix of
atf and gas 1 qt ATF to 5 gal of gas. That helps free up sticking rings and cleans the upper part of the engine

Thank you for the tip. I am actually trying to sell the tractor because I got it at a great deal ($1,500). It is semi-restored looking and operates like a restored tractor minus the highly visible blow-by.

Since I will not be using the tractor any or much at all, can I do 2 gallons of gas and the equivalent part? Should I run it through the engine all at once??

old · Mar 15, 2011

If you do not plan to run it much for say a week or 2 you can just pour about 2 table spoons of ATF in each cylinder and let it sit. That will keep the cylinders from rusting plus keep the rings free and or free them up if they are sticking

sflem849 · Mar 15, 2011

(quoted from post at 14:10:34 03/15/11) If you do not plan to run it much for say a week or 2 you can just pour about 2 table spoons of ATF in each cylinder and let it sit. That will keep the cylinders from rusting plus keep the rings free and or free them up if they are sticking

BUT if you are trying to sell it the tractor will smoke BIG TIME when you first start it up. Not a great selling point so be sure to run it before a viewing appt is setup.

I second checking the breather. I am not a Cub man, but have seen it many times on other machines.

Red Farmer 84 · Mar 15, 2011

Are you saying that it will smoke when the ATF mixture is applied? Will it clear up after running the mixture through the engine completely?

old · Mar 15, 2011

Yes it could smoke a little with the atf and the fule will also have a red color to it. But if you tell the buyer and tell him why the ATF is there it will help no hurt the sell if the guy know engines

Cub Engine Blowby. Is this a problem???

Red Farmer 84

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old

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Jim Becker

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Red Farmer 84

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old

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sflem849

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Red Farmer 84

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old

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